Included in this order are all the spiders. Spiders have 4 pair of legs, no antennae, and from 1 to 4 pairs of eyes. As in all arachnids, the first pair of appendages behind the mouth is called chelicerae and appear as hollow fangs. Poison glands are connected to the fangs and are used to subdue prey. Spiders feed by external digestion. When a spider bites its prey, it injects venom and a digestive enzyme. The function of the digestive enzyme is to dissolve the internal parts of its prey so the spiders can subsequently “suck it dry” with its hollow fangs. Most species of spiders are relatively harmless to humans. In fact the fangs of most spiders are too small and weak to penetrate thicker human skin. A few spiders are potentially harmful to humans and will be discussed.
The black widow spider is found in every state of the country and there are similar species throughout much of the world. There are 5 or 6 species of widow spiders belonging to the genus Lactrodectus in the United States, each being marked slightly different and all of which have a fairly toxic bite. There are 2 species that are restricted to southern Florida, namely the brown widow and the red widow.
Western Black Widow, Lactrodectus Hesperus. This is the species most commonly associated with the name black widow in the Western United States.
A female black widow, Lactrodectus hesperus. Image courtesy James Gathaway CDC Photo Library.
Only the female of the species is dangerous and is named after the practice of her killing the male immediately after copulation. In actuality the female is usually pretty well fed and more times than not the male escapes before being consumed. The males are several times smaller than the females and brownish in color with pearly markings on the top of the abdomen. As with many spiders, the male’s pedipalps are club-shaped and used to transfer sperm to the female.
A male black widow. Image courtesy of Marjory Moody.
The immature females are often brown and striped with colored markings. All stages (except the youngest spiderlings) have a red marking on the underside of the abdomen. This red marking serves as a warning coloration to any potential predator. Bright colors in most animals serve the same function, advertising the fact that this animal is potentially dangerous and to stay away. The black widow female hangs upside down in her web thus making this marking clearly visible.
The female is nocturnal and lies in wait on the web for passing prey. The male typically is not found in the web but hunts either for food or a female. The web is characteristically irregular in shape, strong, and produces a crackling sound when probed. The female can produce from 1 to 10 marble shaped white egg sacs in the spring. These eggs hatch within 10 days or so and the young spiderlings remain inside the sac until after their first molt. The young spiderlings typically leave the sac about 30 days after when the eggs are first laid. There may be as many as 200 spiderlings in each sac. Once emerged they feed on mites and small insects. The life cycle is completed in 4 to 6 months. Black widows typically live about a year. These spiders can be found in many situations but common environment requisites include high humidity, food and dark protected locations.
As with other spiders, black widows balloon or parachute as spiderlings. Ballooning is a term used for the mechanical kiting that many, especially smaller species of spiders, as well as certain mites and some caterpillars use to disperse through the air. Many small spiders use silk to lift themselves off a surface or use the silk as an anchor in mid air. Biologists also apply the term "balloon silk" to the threads that mechanically lift and drag systems.
A spider or spiderling after hatching will climb as high as it can. The spider then stands on raised legs with its abdomen pointed upwards. This is known as "tiptoeing". After that, it starts releasing several silk threads from its abdomen into the air, which automatically form a triangular shaped parachute. The spider can then let itself be carried away by updrafts of winds, where even the slightest of breeze will do. Most rides will end a few meters later, or a spider can be taken up into a jet stream, which depends on its mass, posture, the convection air current, drag of silk and parachute to float and travel high up into the upper atmosphere.
Many sailors have reported spiders have been caught in their ship's sails, over 1600 km from land. They have even been detected in atmospheric data balloons collecting air samples at slightly less than 5 km (16000 ft) above sea level. Apparently it is the most common way for spiders to invade isolated islands and mountaintops. Spiderlings are known to survive without food travelling in air currents of jet streams for 25 days or longer.
It is generally thought that most spiders heavier than 1 mg are not likely to use ballooning. Also, because many individuals die during ballooning, it is more unlikely that adults will do it than spiderlings. Adult females of several social Stegodyphus species (S. dumicola andS. mimosarum), weighing more than 100 mg and with a body size of up to 14 mm, have however been observed ballooning using rising thermals on hot days without wind. These spiders use tens to hundreds of silk strands, which formed a triangular sheet with a length and width of about 1 m.
With black widow and other species spiderlings as temperatures cool and wind turbulence decreases at night, these spiderlings float back to earth. If they reach the prescribed environmental conditions they survive-if not they die. In actuality very few young spiderlings survive to adulthood; however, because the female can produce as many as 2,000 or more spiderlings during her lifetime, only two needs to survive, replace the parents and perpetuate the species.
These spiders are not typically aggressive except in defense of the egg sacs. The fangs of a black widow are quite small and incapable of penetrating thick skin. Consequently a black widow must bite you on the soft parts of your body. The bite of this spider is rather painless at first; however, a systemic effect soon develops because of a strong neurotoxin. The toxin of a black widow is said to be 15 times as toxic as that of a rattlesnake. However, there is much less toxin so the bite is not nearly as bad as that of the snake. Pain begins after 1 to 3 hours and continues for 24 to 48 hours. Pain often starts in the lymph nodes (groin, armpits) and spreads to the lower back. The stomach muscles develop severe cramps due to rigid contractions. The skin feels clammy; blood pressure drops, profuse sweating, and nausea are other symptoms that may develop. Additional symptoms include facial muscle spasms, breathing difficulties and convulsions. The mortality rate of the bite of an adult female black widow in humans is approximately 5% of untreated cases. Most deaths occur in young children (more venom per body mass) or individuals who are already in poor health.
The most common location where black widow bites occur in Southern California is outdoor bathrooms. Right under the toilet seat it is dark, humid and abounds with flies. So in the springtime when the female is guarding her egg sacs and one wiggles her web with soft body parts, it can be quite surprising (ouch!).
There is an antivenin available for bites. This is not always given as it can only be taken once. Frequently hospital patients are given Demerol or something else for the pain if the bite doesn’t seem to be too serious or life threatening. The antivenin is quite effective; however, it is not always advisable to use on all patients as some may develop an allergic reaction.
The black widow antivenin is produced by a fairly complicated procedure. There are a number of small companies that raise black widows by the thousands. Applying a mild electrical shock stimulates the spider to exude a tiny drop of venom from each chelicera. Subsequently, this venom is collected with small capillary tubes and saved. The venom from each company is pooled twice a year in the U.S. to make the antivenin. This is accomplished by injecting small amounts of the venom into horses that already possess a degree of natural immunity to this toxin. After a few weeks when the horses have developed even more immunity as a result of exposure to the venom, serum is condensed from their blood to make the antivenin.
As previously mentioned occasionally individuals treated with antivenin will develop allergic reactions. One such reaction is to develop hives and other symptoms when eating beef. Apparently at least some of the protein in beef is the same or similar to that in horse blood serum. As consequent an allergic reaction unfolds in some cases when beef is consumed.
Control of Black Widows and Other Spiders. Typically pesticide control of spiders is difficult unless you actually see the spider and are able to spray it. There are various insecticides available in retail outlets labeled for spider control, including pyrethrins, resmethrin, allethrin, or combinations of these products. If you spray a spider, it will be killed only if the spray lands directly on it; the spray residual does not have a long-lasting effect. This means a spider can walk over a sprayed surface a few days (and in many cases, a few hours) after treatment and not be affected. Control by spraying is only temporary unless accompanied by housekeeping. It is just as easy and much less toxic to crush the spider with a rolled up newspaper or your shoe or to vacuum it up. Sticky traps offer a noninsecticidal way to remove spiders from your home as long as you can place the traps where pets and curious children can’t tamper with them. Sorptive dusts containing amorphous silica gel (silica aerogel) and pyrethrins, which can be applied by professional pest control applicators only, may be useful in certain indoor situations. Particles of the dust affect the outer covering of spiders (and also insects) that have crawled over a treated surface, causing them to dry out. When applied as a dust-like film and left in place, a sorptive dust provides permanent protection against spiders. The dust is most advantageously used in cracks and crevices and in attics, wall voids, and other enclosed or unused places.
Other Worldwide Black Widows.
Brown Widow Spider-Latrodectus geometricus. This spider is also commonly known as the brown widow, grey widow, brown button spider, or geometric button spider. The brown widow is found in parts of the southeastern, south and southwestern United States (including Florida, Alabama, California, Oklahoma, Nevada, Louisiana, Mississippi, Georgia, South Carolina, Tennessee, Arizona, New Mexico and Texas); as well as in parts of Australia, South Africa and Cyprus. It has recently received considerable attention and has been accidentally introduced Orange County, California and other parts of the country. The origin of this species is uncertain, as specimens were independently discovered in both Africa and in the Americas. They are usually found around buildings in tropical areas.
L. geometricus is generally lighter in color than the black widow species—the color can range from tan to dark brown to black, with shades of grey also possible. Like the black widow species in the United States, L. geometricus has a prominent "hourglass" marking on the underside of the abdomen, however, the brown widow's hourglass is usually a vivid orange or a yellowish color. Unlike the black widow geometricus has a black-and-white "geometric" pattern on the dorsal side of its abdomen. Although the Latin name comes from this pattern, a spider's coloring can and does darken over time and the pattern may become obscured.
Brown widows can be located by finding their egg sacks, which are easily identifiable. They resemble a sandspur, having pointed projections all over, and they are sometimes described as "spiky" in appearance. Eggs hatch in approximately 20 days.
Like all Latrodectus species, L. geometricus has medically significant neurotoxic venom. Dr. G.B. Edwards, a University of Florida arachnologist claims that brown widow venom is twice as potent as the black widow venom, but is usually confined to the bite area and surrounding tissue, as opposed to the black widow. Other sources say that the brown widow is less venomous than L. mactans. Regardless, people who have been bitten typically describe the experience as very painful and extreme care should be taken when working or playing in the areas they inhabit.
Brown Widow Females with an Asymmetrical and Spiked Surface Egg Sac.
Latrodectus mactans, Southern Black Widow. This species is well known for the distinctive black and red coloring and for the fact that she will occasionally eat her mate after reproduction. The highly venomous species is native to the United States of America and Mexico. The female black widow's venom is particularly harmful to humans (males almost never bite humans). The injection of venom from these species is a comparatively dangerous or lethal bite.
Latrodectus mactans was first described by Johan Christian Fabricius in 1775, placing it in the genus Aranea. It is currently placed amongst the Theridiidae family of the order Araneae. The species is closely related to Latrodectus hesperus (western black widow) and Latrodectus variolus (northern black widow). Members of the three species are often confused with the genus Steatoda, the False Black Widows. Prior to 1970, when the current taxonomic divisions for North American black widows were set forth, all three varieties were classified as a single species, L. mactans. As a result, there exist numerous references which claim that "black widow" (without any geographic modifier) applies to L. mactans alone. Common usage of the term "black widow" makes no distinction between the three species.
The mature female is around 1.5 in (38 mm) long and 0.25 inches in diameter. She is shiny and black in color, with a red marking in the shape of an hourglass on the ventral (under) side of her very rounded abdomen. There is much variation in female size, particularly in egg-carrying (gravid) females. The abdomen of a gravid female can be more than 0.5 inch in diameter. Many female widows also have an orange or red patch just above the spinnerets on the top of the abdomen. The male is either black, or closer to the appearance of the juveniles in color, and is much smaller with a body of less than 1/4 inch. Juveniles have a distinctly different appearance than the adults; the abdomen is grayish to black with white stripes running across it and is spotted with yellow and orange.
Southern Black Widow Male with Knobbed Pedipalps. Image Courtesy Joseph Berber, Bugwood.
The southern widow is primarily found in (and is indigenous to) the southeastern United States, ranging from Florida to New York, and west to Texas, Oklahoma, Arizona, and. The northern black widow (L. variolus) is found primarily in the northeastern United States and southeastern Canada, though its range overlaps that of L. mactans. In Canada, black widows range in the southern parts of British Columbia, Alberta, Manitoba and Ontario.
Latrodectus mactans, along with Latrodectrus hesperus and Latrodectus geometricus (the "brown widow spider"), is established in the Hawaiian Islands (USA). One pathway of entry into Hawaii for at least one of these black widow species is imported produce (which is also considered an important potential pathway for widow spiders elsewhere.
When a male is mature, he spins a sperm web, deposits semen on it, and charges his palpi with the sperm. Black widow spiders reproduce sexually when the male inserts his palpus into the female's spermathecal openings. The female deposits her eggs in a globular silken container in which they remain camouflaged and guarded. A female black widow spider can produce four to nine egg sacs in one summer, each containing about 100-400 eggs. Usually, eggs incubate for twenty to thirty days. Rarely do more than a hundred survive through this process. On average, thirty will survive through the first molting, because of cannibalism, lack of food, or lack of proper shelter. It takes two to four months for black widow spiders to mature enough to breed, however full maturation typically takes six to nine months. The females can live for up to five years, while a male's lifespan is much shorter. The female, on occasion, eats the male after mating. Latrodectus mactans is the only black widow species for which this form of sexual cannibalism has been observed in the wild. Lifespans depend upon environment, with shelter being the greatest determining factor and food the second greatest. Males that escape being consumed by the females can go on to fertilize other females. It is a widely held misconception that females eat males after every mating.
Black widow spiders typically prey on a variety of insects, but occasionally they do feed on woodlice, diplopods, chilopods and other arachnids. When the prey is entangled by the web, Latrodectus mactansquickly comes out of its retreat, wraps the prey securely in its strong web, then bites and envenoms its prey. The venom takes about ten minutes to take effect; in the meantime, the prey is held tightly by the spider. When movements of the prey cease, digestive enzymes are released into the wound. The black widow spider then carries its prey back to its retreat before feeding.
There are various parasites and predators of widow spiders in North America, though apparently none of these have ever been evaluated in terms of augmentation programs for improved bio control. Parasites of the egg sacs include the flightless scelionid wasp Baeus latrodecti, and members of the chloropid fly genus Pseudogaurax. Predators of the adult spiders include a few wasps, most notably the blue mud dauber, Chalybion californicum, and the spider wasp Tastiotenia festiva. Other species will occasionally and opportunistically including Mantis or Centipede also can take widows as prey, but these two are general predators and do not significantly reduce population of these spiders.
Although these spiders are not especially large, their venom is extremely potent. Compared to many other species of spiders, their chelicerae are not very large or powerful. In the case of a mature female, the hollow, needle shaped part of each chelicera, the part that penetrates the skin, is approximately 1.0 millimeters (about 0.04 in) long, long enough to inject the venom to a point where it can be harmful. The males, being much smaller, inject far less venom with smaller chelicerae. The actual amount injected, even by a mature female, is very small in physical volume. When this small amount of venom is diffused throughout the body of a healthy, mature human, it usually does not amount to a fatal dose (though it can produce the very unpleasant symptoms of latrodectism). Deaths in healthy adults from Latrodectus bites are relatively rare in terms of the number of bites per thousand people. Sixty-three deaths were reported in the United States between 1950 and 1959. On the other hand, the geographical range of the widow spiders is very great. As a result, far more people are exposed, worldwide, to widow bites than to bites of more dangerous spiders, so the highest number of deaths worldwide is caused by members of their genus. Widow spiders have more potent venom than most spiders, and prior to the development of antivenin, 5% of reported bites resulted in fatalities. The venom can cause a swelling up to 15 cm. Improvements in plumbing have greatly reduced the incidence of bites and fatalities in areas where outdoor privies have been replaced by flush toilets.
Latrodectus tredecimguttatus-Mediterranean Black Widow or Steppe Spider. This is a species of widow spiders in the genus Latrodectus. It is commonly found throughout the Mediterranean region, ranging from Spain to southwest and central Asia, hence the name. Specimens from central Asia are also known by the binomial name Latrodectus lugubris; that name, however, is considered obsolete, though it is still commonly found in the literature. Many consider this spider a Latrodectus mactans subspecies. L. tredecimguttatus bears different names in different regions. For example, in Southern France it is called l'araignée malmignatte. Throughout the Eastern Slavic region (part of Balkans), the name karakurt is most often applied. A direct translation from Turkmen language suggests that kara stands for "black", while kurt might mean "insect" or "bug".
It is black in color, similar to most other widow species, and is identified by the thirteen spots which are found on its dorsal abdomen (the species name is Latin for "thirteen spots"). These spots are usually red in color, but may also be yellow or orange. It is otherwise similar to other species in the genus Latrodectus. The Mediterranean widow primarily lives in steppes and other grasslands, and can be a significant problem in areas where grain is harvested by hand.
Mediterranean Black Widow. Images Courtesy of K. Korlevic.
Like all Latrodectus species, L. tredecimguttatus has a painful bite that is fatal in rare cases. There are many reports of Ukrainian Farm Workers receiving bites while working in fields. In Kazakhstan, there are reports of this species biting and killing camels (probably no true). It is now believed that this species is the cause, often falsely attributed to the wolf spider (Lycosa tarantula).
Redback Spider, Latrodectus hasselti. The female Redback has a round body about the size of a large pea, with long, slender legs. The body is a deep black color (occasionally brownish), often containing an obvious orange to red longitudinal stripe on the upper abdomen. The stripe is sometimes broken or looks like small red dots. On the underside of the abdomen there is an "hourglass" shaped red/orange spot. Juvenile spiders have additional white markings on the abdomen. The male Redback is three to four millimetres long and is light brown in color with white markings on the upper side of the abdomen and a pale hour-glass marking on the underside.
Female Redback Spider. Image Courtesy Peter Chew.
As with other members of this genus the redback web is a disorganized, irregular tangle of fine but strong silk. The rear portion of the web forms a funnel-like retreat area where the spider and egg sacs are found. This area has vertical, sticky catching threads that run to ground attachments.
Redbacks usually prey on insects but they can capture larger animals that become entangled in the web including king crickets, trapdoor spiders and small lizards. Commonly prey stealing occurs where larger females take food items stored in other spiders' webs. Most commonly, ants stray into the web.
Male spiders mature in 37 to 167 days (average in about 90 days). Females mature in 60 to 325 days (average in about four months). Males live for up to 6 or 7 months while female may live for between 2 and 3 years. Even without food spiders may survive for an average of 100 days.
The redback spider is one of only two animals to date where the male has been found to actively assist the female in sexual cannibalism. In the process of mating, the much smaller male somersaults to place his abdomen over the female's mouthparts. In about 2 out of 3 cases, the female consumes the male while mating continues. Males who are not eaten die soon after mating.
Males who sacrifice themselves during mating present two advantages over males who do not. The first is that males who are eaten are able to copulate for a longer period and thus fertilize more eggs. The second is that females who have eaten a male are more likely to reject subsequent males.
Some redback males have been observed utilizing an alternative tactic that also ensures that more of their genetic material is passed on. Juvenile female Redbacks who are nearing their final molting and adulthood have fully formed reproductive organs but lack openings in the exoskeleton that allow access to the organs. Males will bite through the exoskeleton and deliver sperm to the organs without performing the somersault seen in males mating with adult females. The females then molt within a few days and deliver a normal clutch of eggs.
Once the female has mated, she can store sperm and use it over a period of up to two years to lay several batches of eggs. A female spider may lay eggs every 25 to 30 days. A single female normally deposits between 40 and 300 eggs in each sac but can lay up to 5000 eggs. The eggs hatch 13 to 15 days after being laid. Young redback spiders leave the maternal web by being carried on the wind. The spider extends its abdomen high in the air and produces a droplet of silk. The liquid silk is drawn out into a long thread that, when long enough, carries the spider away. Eventually the silken thread will adhere to an object where the young spider will establish its own web.
Its origins are uncertain, and it may have been spread by human activities during the 19th century. Redback spiders are now found in all but the most inhospitable environments in Australia. The redback spider is commonly found in close proximity to human residences. Webs are usually built in dry, sheltered sites, such as among rocks, in logs, shrubs, old tires, sheds, outhouses, children's toys or under rubbish or litter.
Media in Japan have reported the discovery of redback spiders in Osaka, Japan within a hundred kilometers of Kansai International Airport. It was speculated that they arrived in Japan by "hitching" a ride on the outside of airliners, or carried in cargoes of wood chips. In 2008, redback spiders were found in Fukuoka, Japan. Over 700 have been found near the container terminal in Hakata Bay, Fukuoka city. Warning signs about redback spiders have been posted in parks around the city as Japan has had no venomous spider before now.
Redback spiders are also found in small colonies in areas of New Zealand. These spiders were imported on Australian hardwood poles used for electric power and telephone. They are found around Central Otago in the South Island and New Plymouth in the North Island.
Venom is produced by glands in the cephalothorax, and expelled venom travels through paired ducts from the cephalothorax, exiting through the tip of the spider's hollow fangs. The venom of the redback spider is thought to be similar to other Latrodectus spiders and contains a number of high molecular weight proteins, one of which, alpha-latrotoxin (aneurotoxin), is active in humans. In vertebrates alpha-latrotoxin produces its effect through destabilization of cell membranes and degranulation of nerve terminals resulting in the release of neuro-transmitters; it causes uncontrolled release of the neurotransmitters acetylcholine,norephedrine, and GABA. The release of these neurotransmitters leads to the clinical manifestations of envenomation.
Redback spider bites rarely cause significant morbidity, and deaths are even rarer. On Australian record only 14 deaths from redbacks have been recorded. A significant proportion of bites will not result in envenomation or any symptoms developing. It is believed that thousands of people are bitten each year across Australia, although only about 20% of bite victims require treatment. Children and the elderly or those with serious medical conditions are at much higher risk of severe side-effects and death resulting from a bite. No deaths have been reported since the introduction of antivenom in 1956.
The larger female spider is responsible for almost all cases of redback spider bites in humans. The smaller male spider was thought to be unable to inject venom into a human; however, male bites have occurred. The rarity of male bites is probably due to smaller size and proportionally smaller fangs rather than the male being incapable of biting or lacking venom of potency of the female. Cases have shown that the male bite usually only produces short-lived, mild pain.
Most bites occur in the warmer months between December and April and in the afternoon or evening. As the female redback is slow moving and rarely leaves its web, bites generally occur as a result of a person placing a hand or other body part too close to the web, such as reaching into dark holes or wall cavities. But bites can occur wherever the spider may gain access, such as when putting on shoes or dressing.
Bites from redback spiders produce a syndrome known as latrodectism. The symptoms are similar to bites from other Latrodectus spiders. The syndrome is generally characterized by extreme pain and severe sweating. Initially the bite may be painful but sometimes only feels like a pin prick or mild burning sensation. Within an hour victims generally develop more severe local pain with local sweating and sometimes pilo-erection (goose bumps). Pain, swelling and redness spread proximally from the site. Systemic envenoming is heralded by swollen or tender regional lymph nodes; associated features include malaise, nausea, vomiting, abdominal or chest pain, generalized sweating, headache, fever, hypertension and tremor. Rare complications include seizure, coma, pulmonary edema, respiratory failure or localized skin infection. Severe pain can persist for over 24 hours after being bitten.
Medical advice should be sought after being bitten by a redback spider. Usually this requires observation in or near a medical facility for six hours from time of the bite. Treatment is based on the severity of the bite; patients with localized pain, swelling and redness usually do not require any specific treatment apart from applying ice and routine analgesics. In more severe bites the definitive treatment consists of administering redback antivenom. Antivenom will usually give immediate relief to symptoms of systemic envenoming.
Antivenom is indicated in anyone suffering symptoms consistent with Latrodectus envenoming. Particular indications for using antivenom are:
§ Pain and swelling spreading proximally from site
§ Chest pain
§ Abdominal pain
§ Unusual sweating
Currently it is recommended that this antivenom be given intramuscularly (IM) rather than intravenously (IV), although some have suggested that IM antivenom is not as effective as IV antivenom. Adverse reactions to redback antivenom are rare and antivenom may be effective for up to 3 months after a bite. Doses are the same for both children and adults.
RECLUSE, VIOLIN OR FIDDLE BACK SPIDERS
This group of spiders is known as the fiddleback, recluse or violin spiders. Loxoceles reclusa or the brown recluse spider is commonly found in the central and south-central states and Loxoceles laeta or the Chilean brown spider (also known as the South American violin) was found in Los Angeles a number of years ago but recent identifications are non-existent. There is also considerable controversy as to if the brown recluse spider still exists in California. The medical community annually reports treating many bites from the recluse spider. However, spider experts claim this spider no longer exists in California. Because little is known about the effect of the bite of many spider species, it is quite possible that the medically treated cases are not due to the recluse but any of a number of other spiders. This is especially possible when allergic reactions are considered.
Brown Recluse Spider or Violin Spider, Loxosceles recluse. This is a well-known member of the family Sicariidae (formerly placed in a family "Loxoscelidae").
Brown recluse spiders are usually between ¼ in and ¾ inch, but may grow larger. They may be brown, gray, or a deep yellow color and usually have markings on the dorsal side of their cephalothorax, with a black line coming from it that looks like a violin with the neck of the violin pointing to the rear of the spider, resulting in the nicknames fiddleback spider, brown fiddler or violin spider.
Since the violin pattern is not diagnostic, and other spiders may have similar markings (i.e. cellar spiders and pirate spiders), for purposes of identification it is far more important to examine the eyes. Differing from most spiders, which have eight eyes, recluse spiders have six eyes arranged in pairs with one median pair and two lateral pairs. Only a few other spiders have three pairs of eyes arranged in this way, and recluses can be distinguished from these as there are no coloration patterns on the abdomen or legs, which lack spines. The abdomen is covered with fine short hairs. The leg joints may appear to be a slightly lighter color. Other identifying characteristics: Stance on a flat surface usually is with all legs well extended unless alarmed, when it may withdraw its forward two legs straight rearward into a defensive position, withdraw its rear pair of legs into a position for lunging forward, and raise the pedipalps. Movement at virtually any speed is an evenly paced gait with legs extended, stopping naturally when renewing its internal hydraulic blood pressure (that like most spiders is required to renew strength in the legs); it then continues at a steady pace until again it needs to renew its blood pressure. When threatened it usually flees, seemingly to avoid a conflict, and if detained may further avoid contact with fast horizontal rotating movements.
Relative Sized of Adult Recluse and Eye Pattern. Left Image Courtesy of BR-recluse-guy. Right Mattb.
Recluse spiders build irregular webs that frequently include a shelter consisting of disorderly threads. These spiders frequently build their webs in woodpiles and sheds, closets, beds, garages, plenum, cellars and other places that are dry and generally undisturbed. They seem to favor cardboard when dwelling in human residences, possibly because it mimics the rotting tree bark which they inhabit naturally. They also have been encountered in shoes, inside dressers, in bed sheets of infrequently used beds, in stacks or piles of clothes, behind baseboards and pictures, and near sources of warmth when ambient temperatures are lower than usual. Human-recluse contact often is when such isolated spaces are disturbed and the spider feels threatened. Unlike most web weavers, they leave these webs at night to hunt. Males will move around more when hunting, while the female spiders tend to remain nearer to their webs.
The brown recluse spider is native to the United States from the southern Midwest south to the Gulf of Mexico. The native range lies roughly south of a line from southeastern Nebraska through southern Iowa, Illinois, and Indiana to southwestern Ohio. In the southern states, it is native from central Texas to western Georgia north of Virginia and very common in the Northwest particularly Washington State. A related species, the brown violin spider (Loxosceles rufescens), is found in Hawaii. Despite many rumors to the contrary, the brown recluse spider has not established itself in California. There are other species of Loxosceles native to the southwestern part of the United States, including California, that may resemble the brown recluse, but these species have never been documented as physiologically significant.
Symptoms. As indicated by its name, this species is rarely aggressive. Actual brown recluse bites are rare. The spider usually bites only when pressed against the skin, such as when tangled up within clothes, bath towels, or in bedding. Many human victims of brown recluse bites report having been bitten after putting on clothes that had not recently been worn or disturbed. In fact, many wounds that are necrotic and diagnosed as brown recluse bites can actually be methicillin-resistant Staphylococcus aureus (MRSA) or simple staphylococcus infections. Other causes include skin cancer, Lyme disease, and other infected insect bites and skin lesions. Brown recluse bites may produce a range of symptoms known as loxoscelism. There are two types of loxoscelism: cutaneous (skin) and systemic (viscerocutaneous).
Most bites are minor with no necrosis. However, a small number of bites produce severe dermonecrotic lesions, and, sometimes, severe systemic symptoms. These symptoms can include organ damage, and occasionally even death; most fatalities are in children under 7 or those with a weaker than normal immune system. (For a comparison of the toxicity of several kinds of spider bites, see the list of spiders having medically significant venom.)
A minority of brown recluse spider bites form a necrotizing ulcer that destroys soft tissue and may take months to heal, leaving deep scars. The damaged tissue will become gangrenous and eventually slough away. The initial bite frequently cannot be felt and there may be no pain, but over time the wound may grow to as large as 10 inches in extreme cases. Bites usually become painful and itchy within 2 to 8 hours; pain and other local effects worsen 12 to 36 hours after the bite with the necrosis developing over the next few days.
Serious systemic effects may occur before this time, as the venom spreads throughout the body in minutes. Mild symptoms include nausea, vomiting, fever, rashes, and muscle and joint pain. Rarely more severe symptoms occur including hemolysis, thrombocytopenia, and disseminated intravascular coagulation. Debilitated patients, the elderly, and children may be more susceptible to systemic loxoscelism. Deaths have been reported for both the brown recluse and the related South American species L. laeta and L. intermedia. Other recluse species such as the desert recluse (found in the desert southwestern United States) are reported to have caused necrotic bite wounds, though only rarely.
Numerous other spiders have been associated with necrotic bites in the medical literature. A partial list includes the hobo spider and the yellow sac spiders. However, the bites from these spiders are not known to produce the severe symptoms that often follow from a recluse spider bite, and the level of danger posed by each has been called into question. So far, no known necrotoxins have been isolated from the venom of any of these spiders, and some arachnologists have disputed the accuracy of many spider identifications carried out by bite victims, family members, medical responders, and other non-experts in arachnology. There have been several studies questioning danger posed by some of these spiders. In these studies, scientists examined case studies of bites in which the spider in question was positively identified by an expert, and found that the incidence of necrotic injury diminished significantly when "questionable" identifications were excluded from the sample set.
Treatment. First aid involves the application of an ice pack to control inflammation, the application of aloe vera to soothe and help control the pain, and prompt medical care. If it can be easily captured, the spider should be brought with the patient in a clear, tightly closed container so it may be identified. There is no established treatment for necrosis. Routine treatment should include elevation and immobilization of the affected limb, application of ice, local wound care, and tetanus prophylaxis. Many other therapies have been used with varying degrees of success including hyperbaric oxygen, dapsone, antihistamines (e.g., cyproheptadine), antibiotics, dextran, glucocorticoids, vasodilators, heparin, nitroglycerin, electric shock, curettage, surgical excision, and antivenom. None of these treatments have been subjected to randomized controlled trials to conclusively show benefit. In almost all cases, bites are self-limited and typically heal without any medical intervention.
It is important to seek medical treatment if a brown recluse bite is suspected, as in the rare cases of necrosis the effects can quickly spread, particularly when the venom reaches a blood vessel. Cases of brown recluse venom traveling along a limb through a vein or artery are rare, but the resulting mortification of the tissue can affect an area as large as several inches, to the extreme of requiring excising of the wound.
Dapsone is commonly used in the USA and Brazil for the treatment of necrosis. In presumed cases of recluse bites, dapsone is often used effectively, but controlled clinical trials do not demonstrate similar effectiveness; however, dapsone may be effective at treating many "spider bites" because many such cases are actually misdiagnosed microbial infections. There have been conflicting reports about its efficacy and some have suggested it should no longer be used routinely, if at all.
Wound infection is rare. Antibiotics are not recommended unless there is a credible diagnosis of infection. Studies have shown surgical intervention is ineffective and may worsen outcome. Excision may delay wound healing, cause abscesses, and lead to objectionable scarring.
Anecdotal evidence suggests benefit can be gained with the application of nitroglycerin patches. The brown recluse venom is a vasoconstrictor, and nitroglycerin causes vasodilation, allowing the venom to be diluted into the bloodstream, and fresh blood to flow to the wound. Theoretically this prevents necrosis, as vasoconstriction may contribute to necrosis. However, one scientific animal study found no benefit in preventing necrosis, with results showing it increased inflammation and it caused symptoms of systemic envenoming. The authors concluded the results of the study did not support the use of topical nitroglycerin in brown recluse envenoming.
Antivenom, available in South America for the venom of other species of recluse spiders, appears to be the most promising therapy. However, antivenoms are most effective if given early and because of the painless bite patients do not often present until 24 or more hours after the event, possibly limiting the effect of this intervention.
It is estimated that 80% of reported brown recluse bites may be misdiagnosed. The misdiagnosis of a wound as a brown recluse bite could delay proper treatment of serious diseases. There is now an ELISA-based test for brown recluse venom that can determine if a wound is a brown recluse bite, although it is not commercially available and not in routine use.
There are numerous documented infectious and noninfectious conditions (including pyoderma gangrenosum, bacterial infections by Staphylococcus and Streptococcus, herpes, diabetic ulcer, fungal infections, chemical burns, toxicodendron dermatitis, squamous cell carcinoma, localized vasculitis, syphilis, toxic epidermal necrolysis, sporotrichosis, and Lyme disease) that produce wounds that have been initially misdiagnosed as recluse bites by medical professionals; many of these conditions are far more common and more likely to be the source of mysterious necrotic wounds, even in areas where recluses actually occur.
Reported cases of bites occur primarily in Arkansas, Texas, Kansas, Missouri, Colorado, Nebraska and Oklahoma. There have been many reports of brown recluse bites in California (and elsewhere outside the range of the brown recluse); however the brown recluse is not found in California (though a few related species may be found there, none of which has been shown to bite humans). To date, the reports of bites from areas outside of the spider's native range have been either unverified, or—if verified—specimens moved by travelers or commerce. Occasional spiders have been intercepted in various locations where they have no known established populations;Arizona, California, Colorado, Florida, Maine, Minnesota, New Jersey, Mexico, New York, North Carolina, Wyoming and Tamaulipas (Mexico), which indicates that these spiders may indeed be transported fairly easily, though the lack of established populations well outside the natural range also indicates that such movement does not lead to colonization of new areas. Many arachnologists believe that many bites attributed to the brown recluse in the West Coast are not spider bites at all, or possibly instead the bites of other spider species; for example, the bite of the hobo spider has been reported to produce similar symptoms, and is found in the northwestern United States and southern British Columbia. However, the toxicity of the hobo spider has been called into question as bites have not been proven to cause necrosis, and the spider is not considered a problem in Europe. In addition, published work has shown that tick-induced Lyme disease rashes are often misidentified as brown recluse spider bites.
A recent article in National Geographic News exemplifies how common it is to mistakenly blame brown recluse bites on a number of other maladies. “Many diagnoses of brown recluse spider bites come from areas apparently outside of the brown recluse's habitat. Brown recluse spiders are found mostly in the central and southern U.S., an area that includes Texas, Arkansas, Missouri, Kentucky, Tennessee, parts of Illinois, Indiana, and Georgia. Brown recluse spiders also inhabit the states bordering the Gulf of Mexico. Yet Vetter (a UCR spider expert) has fielded reports of brown recluse bites from Wisconsin, New York, even Alaska and Canada. In virtually every case, systematic searches in those places have turned up no brown recluse spiders. In one analysis, Vetter counted 188 reports of brown recluse bites in three years in California, Oregon, Washington, and Colorado. But only 15 brown recluse spiders have ever been found in those four states. "These bite diagnoses are everywhere, and yet no one can find the spider," Vetter said. "Show me the spider."
Even where brown recluses do live, people overestimate their risk, Vetter said. In one recent case in Kansas, a family of four collected more than 2,000 brown recluse spiders in their house during a six-month period. The family found spiders on the paper towel rack, crawling up the stairs, and lurking in piles of laundry. "There were four people living in that house for six years," said Vetter, who wrote about the case in the November issue of the Journal of Medical Entomology."Guess how many bites? None."
Vetter and colleagues have recently embarked on a project to census brown recluse spiders in northern Illinois and southern Iowa. Similar studies elsewhere should provide doctors and the public a better understanding of brown recluse spiders."These spiders are dangerous and they can cause nasty wounds," Vetter said, "but the perception of the brown recluse as a serious health threat is overstated."
Control. The desert recluse is the only Californian recluse of concern and a minor one at that (or the West Coast States as far as that is concerned). After verifying that you do have desert recluses in your home or workplace, there are steps you can take to reduce encounters with them that are similar for reducing encounters with spiders in general. The most important precaution is to remove and reduce trash and rubbish from your property, such as woodpiles, boxes, plywood, tires, and trash cans—especially if they are stored right next to the house. With attached garages, block off house access by sealing cracks around doors and access holes for electrical conduits or plumbing. In the Midwest, some brown recluse bites occur when a sleeping person rolls over during the night, and the trapped spider bites in self defense. In the bedroom, move the bed away from the wall, remove any skirts or ruffles and remove all items stored under it. This minimizes chances that any spider can crawl onto the bed. Do not leave clothes and shoes on the floor, or shake them before dressing if they are left out. Apparel and equipment that is only occasionally worn (gardening clothes and gloves, boots, baseball mitts, roller skates, etc.) should be stored in tightly closed plastic bags, especially if stored in the garage or other dark storage areas.
Typically, pesticide control of spiders is difficult unless you actually see the spider and are able to spray it. There are various insecticides available in retail outlets labeled for spider control. It is just as easy and much less toxic for your living area to crush the spider with a rolled up newspaper or your shoe. Sticky traps placed along floor boards out of the reach of pets and young children offer a non-insecticidal way to trap spiders as well as provide an idea of population levels in the structure. You can also remove a spider from your home by placing a jar over it and slipping a piece of paper under the jar that then seals off the opening of the jar when it is lifted up. If you plan to send the spider to an expert for identification, try to keep it in an undamaged condition because a crushed specimen may be difficult to identify. If you can, soak the spider in rubbing alcohol for a few days to preserve it first. You can freeze the spider first to facilitate safe transfer into alcohol. If you send the spider in for identification, do not mail alcohol as this is a violation of postal regulations unless done exactly to the specifications for mailing flammable fluids.
The brown recluse is a small-to-medium sized spider that is yellow to brown in color with a distinctive violin shape marking on the cephalothorax. These spiders have 6 eyes unlike most spiders that have 8. The web is medium sized, irregular in shape with thick strands and is not typically used to trap insects but rather more as a retreat. The recluse spiders prefer to live in close spaces like between boxes, hanging or folded clothes, etc.
Both the males and females are dangerous. The venom causes a local, necrotic reaction. The victim may not feel any pain for 2 or 3 hours after the bite or a painful reaction may occur immediately. In this case a stinging sensation is usually followed by intense pain. A blister forms as well as a painful, reddish margin. The victim has chills and a generalized rash. The tissue at the center of the bite becomes necrotic and involves the skin as well as subcutaneous tissue. In some cases the necrosis continues to increase resulting in a huge open sore that can reach several inches in diameter. The healing is very slow (up to several months) and often leaves an extensive scar. There is no antivenin available, but the bite is often treated with corticosteroids and excision of the bite area. In advanced cases the lesion may become so large that amputation of limbs may be necessary.
Symptoms of Brown Recluse Spider a Few Days after Bite. Image Courtesy of Center for Disease Control.
Chilean Recluse Spider-Loxosceles laeta. In Spanish, it (and other South American recluse spiders) is known as araña de rincón, or "spider of the corner"; in Portuguese, as Aranha-marrom or "brown spider". This spider is considered by many to be the most dangerous of the recluse spiders, and its bite is known to frequently result in severe systemic reactions, including death.
The Chilean recluse is one of the larger species of recluse spiders, up to 1/12 inches in length (including legs). Like most recluses, it is brown and usually has markings on the dorsal side of its thorax, with a black line coming from it that looks like a violin with the neck of the violin pointing to the rear of the spider resulting in the nickname "fiddleback spider" or "violin spider". Coloring varies from light tan to brown and the violin marking may not be visible. Since the "violin pattern" is not diagnostic, it is far more important, for purposes of identification, to examine the eyes, as with its close relatives.
Chilean Recluse Spider.
The Chilean recluse spider is native to much of South America and can now be found worldwide, including in North and Central America, Finland, and Australia. The spider is known to have established itself in the Los Angeles area, and infestations have been reported in Vancouver, British Columbia, Cambridge, Massachusetts, and Florida. The most recent reports indicate that this species no longer occurs in Los Angeles.
Like other recluse spiders, the Chilean recluse builds irregular webs that frequently include a shelter consisting of disorderly threads. Unlike most web weavers, they leave these webs at night to hunt. People get bitten when they unintentionally squeeze them in clothing and bedding. These spiders frequently build their webs in woodpiles and sheds, closets, garages, and other places that are dry and generally undisturbed. The spider frequently is found in human dwellings. The spiders can last a long time without food or water, a fact that encourages their worldwide spread.
As indicated by its name, this spider is not aggressive and usually bites only when pressed against human skin, such as when putting on an article of clothing. Like all Sicariidae spiders, the venom of the Chilean recluse contains the dermonecrotic agent, sphingomyelinase D, which is otherwise found only in a few pathogenic bacteria. According to one study, the venom of the Chilean recluse (along with the six-eyed sand spider), contains an order of magnitude more of this substance than that of other Sicariidae spiders such as the brown recluse..
Some bites are minor with no necrosis, but a small number produce severe skin necrosis or even systemic conditions (viscerocutaneous loxoscelism); sometimes resulting in renal failure and in 3-4% of cases in a clinical study in Chile, death. The serious bites form a running ulcer that destroys soft tissue and may take months, and very rarely, years to heal, leaving deep scars. The damaged tissue will become gangrenous and eventually slough away. Initially there may be no pain from a bite, but over time the wound may grow to as large as 10 inches in extreme cases. Bites may take up to seven hours to cause visible damage; more serious systemic effects may occur before this time, as venom of any kind spreads throughout the body in minutes.
First aid involves the application of an ice pack to control inflammation, the application of aloe vera to soothe and help control the pain, and prompt medical care. If it can be captured, the spider should be brought with the patient in a clear, tightly closed container for identification. However, by the time the bite is noticed any spider found nearby is not likely to be the culprit. Unfortunately, 50% of children bitten in South America die without treatment. Antivenin is available in South America. The bite’s progress is slightly different from the recluse in that the ulcerated area is dark rather than white. This spider is a hunting spider that searches for prey away from its web and is nocturnal.
Desert Recluse Spider-Loxoceles deserta. This is another relative of the more notorious brown recluse or violin spider. The distribution of this species in California is quite limited occurring in isolated desert areas above 3,000 feet elevation. This is a medium-sized, non-descript tan species with many fine hairs covering the body. Very few people are bitten by this species and the symptoms are similar, but far less severe, than that of the South American violin or brown recluse spiders.
Very little is known about the bite or symptoms of the other recluse spiders that are found in the United States. The distribution of these as is follows:
The Tucson recluse, Loxoceles Sabina. Limited to Tuscon area.
The Arizona recluse, Loxoceles arizonica. Central and southern Arizona and SE California.
The Baja recluse, Loxoceles palma. Baja and S.California.
The Big Bend recluse, Loxoceles blanchi. Western Texas.
The Grand Canyon recluse, Loxoceles kaiba. Grand Canyon.
Matha’s recluse, Loxoceles martha.
The Mediterranean recluse, Loxoceles rufescens. Introduced species, several US cities. Bite not considered as toxic as some
of the other species.
Russell’s recluse, Loxoceles russelli. Death Valley.
The Texas recluse, Loxoceles devia. Texas.
The Tucson recluse, Loxoceles sabina. Tucson area.
The Hobo Spider (Tegenaria agrestis). This is a member of the genus of spiders known as funnel web spiders. It is one of a small number of spiders in North America whose bites are generally considered to be medically significant. Individuals construct a funnel-shaped structure of silk sheeting and lie in wait at the small end of the funnel for prey insects to blunder onto their webs. Hobo spiders sometimes build their webs in or around human habitations. Although this species of spider has a reputation for aggressiveness even though they will normally avoid contact with humans. Most bites occur when the spider is accidentally crushed or squeezed by a human. The spider's venom is strong enough to cause considerable local pain and possibly necrosis.
The toxicity and aggression of the hobo spider are currently disputed by arachnologists. Its nickname "aggressive house spider" comes from a misinterpretation of the Latin name agrestis, which literally translates to "of the fields", but has been mistranslated as "aggressive". If a hobo spider is tending an egg sac, it may become aggressive if it perceives the egg sac as being threatened. However, they generally do not bite unless forced to protect themselves, and in the majority of cases the hobo spider does not actually inject venom when it does bite.
In the United States, the hobo spider has been considered to be a dangerous species based on a toxicology study on rabbits where lesions appeared after spiders were induced to bite the rabbits, although attempts to replicate the study (by injecting venom to ensure envenomization) have failed to produce necrotic lesions, and there is even question as to whether the lesions observed in the original study were necrotic. This laboratory study has led to the proposal that in some parts of the U.S. nearly all bites imputed to the brown recluse spider are in reality the hobo spider's bite. The CDC and other U.S. government agencies have also used this same study as the basis for a report claiming that the hobo spider bite causes necrosis in humans despite the absence of any confirmed cases. In Canada, there are scientists who claim that no hobo spider bites lead to dermal necrosis. Hobo spiders are common in Europe, though bites are relatively unknown, and there are no confirmed reports of them causing necrosis despite hundreds of years of coexistence there. The only documented case of a verified hobo spider bite leading to necrotic skin lesions involves a person who had a pre-existing medical condition (phlebitis) that can also cause the appearance of skin lesions.
Hobo spider bites are not known to be fatal to healthy humans. The necrosis in purported cases is similar to, but milder than, that caused by the brown recluse spider, and in severe cases can take months to heal. Other reported symptoms include intense headaches, vision abnormalities, and/or general feelings of malaise. These symptoms are not confirmed for the hobo spider bite specifically due to lack of positive identification of the spider by an expert, and the Oregon Poison Center (affiliated with the Oregon Health & Science University) is attempting to gather definitive evidence regarding the validity of these reports as of September 2007.
In females, the body measures between 5 and 9mm and in males, 4 to 8mm. The leg span however can be up to 1 inch with the front pair of legs being longer than the other 3 pairs. Males tend to have a skinnier body and a larger leg span than females. C. Inclusum gets its 2 common names (yellow sac and black-footed spider) from its appearance. It is a pale yellow-beige color with dark brown markings on its palps, chelicerae (jaws) and on the ends of its tarsi (feet). There is also often an orange-brown stripe running down the top-centre of its abdomen. In terms of sensory structures, C. Inclusum has 8 similarly sized eyes distributed in 2 parallel horizontal rows. However their eyes are thought to be less important structures due to the absence of light during the spider's nocturnal activity. The spider relies more on palps, sensory structures just behind the chelicerae on the cephalothorax, to sense its environment.
Females of C. inclusum mate only once, and produce their first egg mass about 14 days after mating. Two sets of eggs are usually produced, but this can range anywhere from 1 to 5. Egg masses generally contain 17 to 85 eggs, although as many as 112 eggs have been reported in a single egg mass. Egg lying generally occurs during the months of June and July; during this period, females lay their eggs in small (2 cm) silk tubes and enclose themselves with the eggs, protecting them from predators. Females stay with the eggs and juvenile spiders for about 17 days - until their first complete molt. Females that produce multiple egg masses build a second egg sac about two weeks after the juvenile spiders disperse. Males tend to mature faster (119 days on average) than females (134 days on average), but time to maturity can range from 65 to 273 days depending on a number of factors, such as temperature, humidity and photoperiod. They over-winter mostly as adults or sub-adults.
Being nocturnal, this spider feeds and mates at night. C. inclusum do not make webs to catch prey; instead, they are active predators, feeding on a variety of arthropods such as insects and other spiders. Prey detection may involve detection of mechanical vibrations of the substrate, and vision seems to play an insignificant role. During the day, they retreat in small silk nests similar to those used for reproduction. A new nest, which may be completely closed, open on one side, or open on both sides, is built every day in under 10 minutes. C. inclusum are known to disperse easily between trees and shrubs. They do this by excreting a long silk thread that gets carried by the wind and sticks to a nearby structure, forming a scaffold between two structures. Alternatively, the spider may stay attached to the thread and become airborne as the wind carries the thread in the air.
The bite of these spiders is believed to be venomous to humans but rarely produces more than local symptoms. They are believed to produce a high percentage of the spider bites suffered by people, possibly because they wander about when people cannot see well or are asleep, and so they may get squeezed and bite to protect themselves. Bites that occur to farm laborers may occur because spiders hiding in their shelters on leaves may get squeezed.
It has been noted that a large number of bites attributed to the brown recluse spider may actually be the result of yellow sac spider bites, which possess a cytotoxic venom known to contain several proteolytic enzymes including alkaline phosphatase, deoxyribonuclease, esterase, hyaluronidase, lipase, and ribonuclease. These enzymes can cause localized tissue necrosis (which may be similar to that caused by a recluse bite), though the symptoms are less severe and do not result in the systemic effects occasionally seen with recluse envenomations.
However, the view that this spider is dangerous to humans has been questioned. A recent study of 20 confirmed yellow sac spider bites revealed no evidence of necrosis; further review of international literature on confirmed bites revealed only a single bite with mild necrotic symptoms.
Although the danger of C. inclusum may be questionable, the spider bite may cause local redness with stinging pain. When it's found immediately wash from the bite site to prevent further venom entering the wound in case of the spider bite. Thoroughly wash the wound with soap and water. Do not use alcohol. Also do not engage in any activity that raises the heart rate. An ice pack may be applied to draw out the venom. Do not squeeze or pick the bite site. It may cause secondary infection or spread the poison to a wider tissue region. If the pain persists for a long period, show it to a doctor for a proper measure.
C. inclusum bites usually occur when the spider is threatened. People might threat C. inclusum without noticing in some incidents. For example, while C. inclusum is hunting during the night time, people may roll over and press the spider accidentally or put on a coat that stayed in the closet over the winter without noticing the spider inside. Also, putting the shoes on while C. inclusum is in there. As the weather cools down, it is more likely for the spider to invade the indoor structures. To prevent the bite from C. inclusum, secure all the screens on the windows and doors. Do not stack up the fire woods near the house. Also, take care of all the house pests such as ants and silverfish that attract spiders.
An adult yellow sac spider. Image courtesy of Joseph Berger, Bugwood.
Tarantulas have received a “bad rap” from the moving picture industry for years. Actually in most cases the bite of a tarantula is relatively harmless to humans. That is to say the venom has little more effect than that of a bee sting. Of course, as tarantulas are so large, it follows that their chelicerae are large. In some of the large species of the world these structures can reach one inch in length. In this case the bite will result in a deep puncture wound and should be treated with a tetanus shot. As with many species of spiders little is known about the toxicity of the venom of many tarantula species. This knowledge is becoming increasingly important because of the recent interest in keeping tarantulas as pets. There are many tarantula breeders in the United States and Europe. These individuals conservatively rear over 100 species of tarantulas for the pet and spider enthusiast trade.
Besides biting, New World tarantulas frequently protect themselves by kicking off puffs of branched body hairs from the back of their abdomens with their hind legs. The mucous membrane of the eyes and nose of mammals, including humans, are quite sensitive to these hairs and resultant watery eyes and severe itching of the skin may last for several hours. These hairs can penetrate the skin up to 1/16 inch and frequently have a toxin associated with them. People who handle tarantulas may develop an allergic reaction to this venom, causing increased sensitivity and irritation after minimal contact. Because the venom in the hairs is likely to be the same as that in the fangs, someone who has developed sensitivity to the hairs could have a more severe reaction upon being bitten. The hairs are regenerated each time the tarantula molts.
Chelicera or fangs of an average sized tarantula.
A goliath tarantula -with its legs spread. This is one of the largest species of tarantula-
often reaching the size of a dinner plate.
OTHER SPIDERS THAT BITE
All spiders have fangs and poison glands (there are a few exceptions); however, many are timid and will not or cannot penetrate the skin because their fangs are too small. There is a tremendous lack of knowledge about the effect of the bite of many common spiders in the world. A good example of this is the brown recluse. As mentioned above spider experts strongly feel that this spider no longer exists in California. However, as with many other hospitals, Redlands Community (a Southern California hospital) reports treating several brown recluse bites a year. If the spider experts are correct, there must other species of which we are not aware, whose bite produces symptoms similar to that of the brown recluse.
Jumping Spider-Family Salticidae. The jumping spiders are reportedly very aggressive and on occasion bite humans. The venom is not very potent and the bite is initially painful leaving 2 small red marks that heal in a few days. Johnson’s jumping spider is the most common species that has been reported to bite humans. This outdoor species is nearly 1/2 inch long (big for a jumping spider) and has a black head with a black and red body.
Jumping spider that occasionally bite. Image courtesy of Opoterser
This family contains more than 500 described genera and about 5,000 described species, making it the largest family of spiders with about 13% of all species. They have good vision and use it for hunting and navigating. They are capable of jumping from place to place, secured by a silk tether.
Jumping spiders live in a variety of habitats with tropical forests harboring the most species, but they also commonly occurring in temperate forests, scrub lands, deserts, intertidal zones, and even mountains. Euophrys omnisuperstes is a species reported to have been collected at the highest elevation on the slopes of Mount Everest.
They are generally diurnal, active hunters. They possess a well-developed internal hydraulic system which alters the pressure of body fluid within their legs thus allowing the spiders to jump without large muscular legs. Some jumping spiders can jump 40 times their body length. This is equivalent to a 6 foot man jumping 240 feet. When moving and especially just before it jumps, the spider tethers a filament of silk to any available surface. Should it fall, it can then climbs back up the silk tether. These spiders are capable of jumping over 40 times their length.
Jumping spiders are known for their supposed curiosity. For example if approached by a human hand, instead of retreating to safety as most spiders would, the jumping spider will usually leap and turn to face the hand. Further approach may result in the spider jumping backwards while still eyeing the hand. The tiny creature will even raise its forelimbs and hold its ground. Because of this contrast to other arachnids, the jumping spider is regarded as inquisitive as it is seemingly interested in whatever approaches it.
An additional distinctive characteristic is their large eyes. These spiders have the best-developed visual system of all spiders, which is used to best advantage when hunting prey. As do most spiders, they have 4 pairs of eyes. One large pair and 1 small pair are oriented in a forward facing position. Above this front row is a second row of 2 tiny eyes and behind these there is a set of 2 large eyes oriented in an upward position. As a result these spiders can see in a 360-degree plane. Unlike other spiders they can move their eyes outward or inwards for focusing and they can be turned up and down and from left and right. The spider can also turn its carapace (breast) more than 45 degrees to look around. Jumping spiders have very good vision centered in their anterior median eyes. Their eyes are able to create a focused image on the retina, which has up to four layers of receptor cells. Physiological experiments indicate that they have up to four different kinds of receptor cells, with different absorption spectra, giving them the possibility of up to tetrachromatic color vision, with sensitivity extending into the ultraviolet range. All salticids are highly sensitive to UV light. The principal eyes have high resolution, but the field of vision is narrow, from 2 to 5 degrees.
Jumping spiders are active hunters stalking their prey. They use their superior eyesight to distinguish and track their intended meals, often for several inches. Then, they pounce, giving the insect little to no time to react before succumbing to the spider's venom.
Jumping Spider with Heavily Fringed Palps for Mating Display. Image Courtesy of Peter Chew.
Mating recognition depends on visual courtship displays. Males are often quite different in appearance than females and may have plumose hairs, colored or iridescent hairs, front leg fringes, structures on other legs, and other, often bizarre, modifications. These are used in visual courtship in which the colored or iridescent parts of the body are displayed via vibrations, or zigzag movements for courtship "dance". If the female is receptive to the male she will assume a passive, crouching position. In some species, the female may also vibrate her palps or abdomen. The male will then extend his front legs towards the female to touch her. If the female remains receptive, the male will climb on the female's back and inseminate her with his palps. In recent years it has been discovered that many jumping spiders may have auditory signals as well, with amplified sounds produced by the males sounding like buzzes or drum rolls.
Trapdoor Spiders. Family Ctenizidae. Trapdoor spiders are mygalomorph spiders that construct burrows with a cork-like trapdoor made of soil, vegetation and silk. These relatively large spiders (adults reaching 1 to 1.5 inches in length) are rarely seen as they spend the majority of their lives in well-designed tunnels in the ground. The only time that a trap door spider is commonly seen is when the male reaches sexual maturity and strikes out in search of a female. Otherwise they remain, grow and molt inside their tunnels. The entrance of the tunnel is typically covered by an earthen door that is hinged at one end. The door is extremely difficult to spot as it blends in with the surrounding environment.
A trap door spider.
Trap door spiders do not leave their burrows to hunt but merely wait with the door partially open for passing prey. Their eyesight is not well developed and they rely on sensitive hairs on their legs to pick up the vibrations of a passing prey. Some species actually place elongated twig or silken strands radiating out from the entrance to increase the distance of detection from the entrance.
The door of a trap door spider with silken stands and twigs radiating outward to detect potential prey.
The burrow and door serve not only as a home and means to capture prey, but also protects the spiders from rain, regulates the humidity and temperature, and helps protect them from potential predators, such as centipedes, scorpions and parasitic wasps. In some species the spider has a set of spines on its legs, which it presses into the side of the burrow while it holds the door shut with its fangs. We once tried to pry open the door of one of these spiders with a spoon and actually bent the handle in doing so. It is now known that this spider can withstand the pull of 38 times its weight.
A hungry individual will wait halfway outside of its burrow for a meal. Male trapdoor spiders can overcome the female's aggressive reactions to their approach, but it is not known how. Females never travel far from their burrows, especially if they have an egg sac. During this time, the female will capture food and regurgitate it to feed her spiderlings. Enemies of the trapdoor spider include certain pompilids (spider wasps), which seek out the burrows and manage to gain entrance. They sting the owner and lay their eggs (usually one per spider) on its body. When the egg hatches, the larva devours the spider alive.
Unlike other mygalomorph spiders, the Ctenizidae have a rastellum on the chelicera. This structure resembling "teeth" or "barbs" on each fang is used to dig and gather soil while constructing a burrow.
Some species store the remains of their prey and other debris behind the silk lining of the tunnel. If a potential predator breaks into the tunnel, the spider will rush to the bottom of the tunnel while simultaneously releasing the debris and silk lining, thus forming a false bottom to the tunnel and concealing the spider beneath.
Hollywood Trapdoor Species. Aptostichus stephencolberti is a species of trapdoor spider named after the American satirist Stephen Colbert. The spider was discovered on the California coastline in 2007. This species is found on coastal dunes that extend from the Big Sur area to the San Francisco peninsula at Point Lobos and Golden Gate. Compared to closely-related species such as Aptostichus angelinajolieae (named after Angelina Jolie), Aptostichus stephencolberti is lighter in color. The male holotype and the female paratype both have brownish yellow legs, carapace and chelicerae, while the abdomen is lighter with dusky stripes. The male has six teeth, while the female has five.
The spider was named after Colbert after he reported on his television series The Colbert Report that Jason Bond, a professor of biology at East Carolina University, named a different species of spider Myrmekiaphila neilyoungi, after the Canadian rock star Neil Young. Colbert was angered by the fact that Bond had not named a spider after him, and began to appeal for a species of animal to be named after him. He claimed that he already had an eagle and a turtle named after him, so there was no reason that another animal could not be named after him as well.
On a later edition of The Colbert Report, Colbert revealed that Bond would name a spider after him, with Colbert claiming, "And all I had to do was shamelessly beg on national television." The two men talked on the telephone to decide which spider should be the one to be so named, but as there were 27 different species of spider available, Bond was left to make the final choice.
The name Aptostichus stephencolberti was officially announced as the spider named after Colbert on The Colbert Report on August 6, 2008. Because Colbert pronounces his surname with a silent "T", the last "T" in stephencolberti is also silent.
The Grass Spiders. This is another species of common spider that reportedly bites humans. This species is a little less than ½-inch in length with 2 dark parallel stripes running the length of the cephalothorax. The overall body color is tan with modeled white markings. This spider inhabits gardens and junk piles and lives under stones and logs. The web is trampoline-like in shape and tapers back into a funnel where the spider hides and waits for its prey. This species can produce a painful bite due to its powerful jaw muscles and large fangs. The nature of the venom is unknown. Typically a bite will cause mild swelling and a red spot. There have been some recorded cases of more severe symptoms. This could possibly be due to allergic reactions to the venom.
A grass spider frequently bites resulting in mild swelling.
Orb Weaver Spiders. Family Araneidae. Characterized by spiral wheel-shaped webs they are often found in gardens, fields and forests. Their common name is taken from the round shape of this typical web. Orb-weavers have eight similar eyes, legs hairy or spiny and no stridulating organs. The family is cosmopolitan, including many well-known large or brightly colored garden spiders. There are more than 2,800 species in over 160 genera worldwide, making this the third largest family of spiders known behind Salticidae and Linyphiidae.
Generally, orb-weaving spiders are three-clawed builders of flat webs with sticky spiral capture silk. The building of a web is an engineering feat, begun when the spider floats a line on the wind to another surface. The spider secures the line and then drops another line from the center, making a "Y". The rest of the scaffolding follows with many radii of non-sticky silk being constructed before a final spiral of sticky capture silk. The third claw is used to walk on the non-sticky part of the web. Characteristically, the prey insect that blunders into the sticky lines is stunned by a quick bite and then wrapped in silk. If the prey is a venomous insect, such as a wasp, wrapping may precede biting.
Many orb-weavers build a new web each day. Generally, towards night, the spider will consume the old web, rest for approximately an hour, and then spin a new web in the same general location. Thus, the webs of orb-weavers are generally free of the accumulation of detritus common to other species such as black widow spiders.
Some orb-weavers do not build webs at all with these include members of the genera Mastophora in the Americas, Cladomelea in Africa and Ordgarius in Australia. This group of spiders has a rather unique means of catching their prey. They are part of a tribe of the orb-weaving spider family (Araenidae) that no longer build an orb web, but instead attract their prey (male moths) by chemical mimicry. The moths are captured using a "bolas" which is a sticky ball of glue attached to a strand of silk. The spider swings this around until the ball hits and sticks to the approaching moth. The moth is then reeled in by the spider and then webbed up in silk. This would be a pretty inefficient means of capturing prey if done at random. The chance of catching a moth that merely flew by would be pretty remote. However, the spider actually emits a sex pheromone that mimics that produced by female moths to attract males for mating. Instead of finding a mate the males end up as dinner for the bolas spider. Even more amazing this spider feeds on 2 different species of moths each of which fly and typically mate at different times of the night-one early in the evening and another late at night. Accordingly the bolas spider produces and releases 2 different pheromones each at the correct time that correspond to when each species flies.
An Australian female bolas spider. Image courtesy of Dave Britton.
An American bolas spider swinging its sticky ball. Image courtesy of Dave Britton.
An equally amazing feature of this spider is the huge size of their egg sacs. Typically several of these giant are produced by the female. It is thought that she is capable of doing this due to the small amount of silk used in catching her prey.
A female bolas spider sitting on one of its several egg masses. Image courtesy of Dave Britton.
The spider produces sticky globules, which contain a pheromone analog. The globule is hung from a silken thread dangled by the spider from its front legs. The pheromone analog attracts male moths of only a few species. These get stuck on the globule and are reeled in to be eaten. Interestingly, both types of bolas spiders are highly camouflaged and difficult to locate.
The spiny orb-weaving spiders in the genera Gasteracantha and Micrathena look like plant seeds or thorns hanging in their orb-webs. Some species of Gasteracantha have very long horn-like spines protruding from their abdomens.
One feature of the webs of some orb-weavers is the stabilimentum, a crisscross band of silk through the center of the web. It is found in a number of genera, but Argiope, which includes the common garden spider of Europe as well as the yellow and banded garden spiders of North America, is a prime example. The band has been hypothesized to be a lure for prey, a marker to warn birds away from the web and a camouflage for the spider when it sits in the center of the web. However, recent research suggests that the stabilimentum actually decreases the visibility of the silk to insects, thus making it harder for prey to avoid the web
Most arachnid webs are vertical and the spiders usually hang with their head downward. A few webs, such as those of orb-weaver in the genus Metepiera have the orb hidden within a tangled space of web. Some Metepiera are semi-social and live in communal webs. In Mexico such communal webs have been cut out of trees or bushes and used for living fly paper.
The oldest known true orb-weaver is Mesozygiella dunlopi, from the Lower Cretaceous. Several fossils provide direct evidence that the three major orb weaving families, namely Araneidae, Tetragnathidae and Uloboridae, had evolved by this time, about 140 million years ago. They probably originated during the Jurassic (200-140 million years ago). All three families very likely have a common origin.
Lynx Spiders-Family Oxyopidae . Lynx Spiders are hunting spiders that spend their lives on plants, flowers and shrubs. Nimble runners and jumpers, they rely on their keen eyesight to stalk, chase or ambush prey. Six of their eight eyes are arranged in a hexagon-like pattern, a characteristic that identifies them as members of the family. They also have spiny legs. Common genera in the United States include Oxyopes—the common lynx spiders—and Peucetia—the green lynx spiders.
Some members of the genus Oxyopes are abundant enough to be important in agricultural systems as biological control agents. This is especially true of the striped lynx spider (Oxyopes salticus). A member of the genus Tapinillus is remarkable as being one of the few social spiders, living in colonies.
Peucetia viridans, the green lynx spider, is a conspicuous bright-green spider found on shrubs. It is the largest North American lynx spider. The species name, viridans, is Latin for "becoming green".
The female reaches a body length approaching an inch in length; the more slender male averages ½ inch. There usually is a red patch between the eyes, with red spots over the body. The eye region is clothed with white appressed hairs. The legs are green to yellow, with very long black spines, and covered with black spots. It is rather similar to other species to occur in the United States. Gravid females are able to change their color to fit their background; however, this takes about 16 days.
The green lynx spider is capable of spitting its venom a few inches. Image courtesy of Russ Ottens, Univ. Georgia.
The female constructs one to four egg sacs in September and October, each containing 25 to 600 bright orange eggs, which she guards, usually hanging upside down from a sac and attacking everything that comes near. The eggs hatch after about two weeks, and after another two weeks fully functional spiderlings emerge. They pass through eight instars to reach maturity. this non venomous spider is usually found on foliage.
The green lynx spider very seldom bites humans, and its bite is harmless though painful. It is a common predator in cotton and other crops. This species is found in gardens, chaparral, on flower heads of wild buckwheat, in tall grass and bushes where it hunts and captures its prey without the use of a web. The green lynx is capable of biting and spitting its venom a distance of a few inches. If it reaches the eyes the venom may cause irritation that will clear up in a few days. The spiders have been observed to hunt several moths species and their larvae, including some of the most important crop pests, such as the bollworm moth (Heliothis zea), the cotton leaf worm moth (Alabama agrillacea) and the cabbage looper moth (Trichoplusia ni). However, they also prey on beneficial insects, such as honey bees.
Wolf Spiders-Lycosidae. The family name Lycosidae, from the Greek word "λύκος" means "wolf". They are robust and agile hunters with good eyesight but unlike wolves but live mostly solitary lives and hunt alone. Some are opportunistic wandering hunters, pouncing upon prey as they find it or chasing it over short distances. Others lie in wait for passing prey, often from or near the mouth of a burrow.
Wolf spiders resemble nursery web spiders (family Pisauridae), but they carry their egg sacs by attaching them to their spinnerets (Pisauridae carry their egg sacs with their chelicerae and pedipalps). Wolf spiders have two eyes out of eight that are large and prominent. The eight eyes of the Nursery web spiders are all of approximately equal size.
There are many genera of wolf spider, ranging in body size from less than 1 to 0.04 to 1.18 inch. They have eight eyes arranged in three rows. The bottom row consists of four small eyes, the middle row has two very large eyes, and the top row has two medium-sized eyes. They depend on their eyesight, which is quite good, to hunt. Their sense of touch is also acute.
Eye Configuration of Wolf Spider. Image Courtesy Opoterser.
Wolf spiders are unique in carrying their egg sac, which they attach to the spinnerets at the end of their abdomen. The abdomen is held in a raised position to keep the egg case from dragging on the ground, but they are still capable of hunting while so encumbered.
Also unique to wolf spiders is their method of infant care. Immediately after the little spiders hatch and emerge from their protective silken case, they clamber up their mother's legs and all crowd onto her abdomen.
Female Wolf Spider Carrying Spiderlings. Image Courtesy Wikipedia Commons.
Their eyes readily reflect light. One method of finding them is to hunt at night using a flashlight strapped on the forehead so that the light is reflected from their eyes directly back toward its source. Because they depend on camouflage for protection, they do not have the flashy appearance of some other kinds of spiders. In general their coloration is appropriate to their favorite habitat.
Hogna is the genus with the largest of the wolf spiders. Among the Hogna species in the U.S., the nearly solid dark brown H. carolinensis is the largest, with a body that can be more than one inch long. It is sometimes confused with H. helluo (pictured below), which is somewhat smaller and entirely different in coloration.
Some members of the Lycosidae, such as the Carolina wolf spider make deep tubular burrows in and around which they lurk much of the time. Others, such as H. helluo, seek shelter under convenient rocks and other such shelters as nature may provide. They may wander from place to place, and are therefore more likely to be the ones attracted into human habitation when the weather starts to turn colder in autumn.
There are many smaller wolf spiders. They patrol pastures and fields and are an important natural control on harmful insects.
Wolf spiders are capable of defensive bites, and some South American species may give bites that are medically significant. Wolf spiders will inject venom freely if continually provoked. Symptoms of their bite include swelling, mild pain and itching. Though usually considered harmless to humans, the bite of some species can be painful. In the past, necrotic bites have been attributed to some South American species, but further investigation has indicated that those problems that did occur were probably actually due to bites by members of other genera. Australian wolf spiders have also been associated with necrotic wounds, but careful study has likewise shown them not to produce such results.
Wolf spiders can be found in a wide range of habitats both coastal and inland. These include shrub lands, woodlands, wet coastal forests, alpine meadows, and suburban gardens. Spiderlings disperse aerially (ballooning) and consequently wolf spiders have wide distributions. Although some species have very specific microhabitat needs most are wanderers without permanent homes. Some build burrows which can be opened or have a trapdoor. Arid zone species construct turrets or plug their holes with leaves and pebbles during the rainy season to protect themselves from flood waters.
Araneomorph Funnel-Web Spiders-Agelenidae. Other common names of these spiders include funnel weavers, cobweb and grass spiders. Because many other spiders are similar in appearance to them, these spiders are most easily distinguished by the shape of their webs rather than the spiders themselves. They weave a tubular funnel, which is used as a retreat and is located at one the silken sheet of the web. Any prey that lands on the sheet is caught and consumed in the retreat. The egg sac is found in the funnel and the male often stays with the female, which is rare in arthropods and becoming somewhat rare in human marriages. As the second common name suggests, they can be found in tall grass. These spiders occasionally enter homes. This is certainly not their normal habitat and typically results from the males wandering and looking for a female and blundering into the structure. The human female they find there is usually not so happy to see them.
A common funnel web, cobweb or grass spider. Image courtesy of Joseph Berger-Bugwood.
This family includes the common grass spiders of the genus Agelenopsis, as well as the purportedly venomous European hobo spider, Tegenaria agrestis, which has been introduced into the Pacific Northwest of the United States. The araneomorph funnel-web spider should not to be confused with the funnel-web tarantula and the venomous funnel-web tarantula. The venomous funnel-web tarantulas include the infamous Sydney funnel-web spider.
There are nearly 500 species in over 40 genera worldwide. Among other genera are Hololena and Agelena. The last named genus includes some fascinating semi-social spiders that live in complex communal webs in Africa. The best known of these is probably Agelena consociata.
Sociality in these spiders has gone so far as communal web-building and sharing; cooperative prey capture and communal rearing of young. Spiders have not, however, taken the final step into the social behavior of the social Hymenoptera (ants, bees and wasps) because there are no workers or soldiers (no castes) and all females are reproductive.
Most of these spiders are also known for their fast speed which, on the web, can reach 2 km/h (slow-paced pedestrian walk). Due to this ability, they practically rely solely on their movement while capturing prey, but, unlike similar families, Lycosidae for example, they prefer to stalk their prey by building randomly placed web sheets, which may include up to 100 times the spider's size and funnel down to a narrow nest, hence the spider's name.
Funnel Web Spider in Web. Image Courtesy of Pollinator en Wikipedia.
Usually, Agelenids range from 1/4 to ½ inch in size, excluding leg span, and about 2 inches in the largest species, including the legs.
Agelenids have a disputable reputation of a bite that could be highly venomous to humans, however, this has never been completely proven. Of all the genera, Tegenaria species probably have the most potent venom, but cases of a medically considerable spider bite occurring from them are generally scarce.
DaddyLongleg Spiders-Family Phlocidae. Some species, are alos commonly called granddaddy long-legs spider, daddy long-legger, cellar spider, vibrating spider, or house spider. Pholcids are fragile spiders, the body being 1/10 to 4/10 in length with legs which may be up to 2 inches long. They have cylindrical abdomens and the eyes are arranged in two lateral groups of three and two smaller median contiguous eyes. Eight and six eyes both occur in this family. Other species have a small globose abdomen with eyes are arranged in two groups of three and no median eyes. Pholcids are gray to brown with banding or chevron markings.
These spiders have very long legs and look similar to the harvestmen or true daddy longlegs. The harvestmen are not true spiders and actually belong to a separate order (Phalangida), as discussed earlier. An easy way to distinguishing the two is that the true daddy longleg has a segment abdomen while the spider does not. The members of the daddy-longlegs spiders are the most common spiders that are found in houses and buildings. My wife really like spiders and doesn’t want me killing these spiders that inhabit our house. Consequently we don’t have to decorate that much for Halloween. When it gets really bad I sometimes sneak out with the vacuum at night. When disturbed or under threat of attack, they violently vibrate their web in attempt to discourage the intruder, hence another common name of the vibrating spiders. Some indications are that this spider has very toxic venom; however, their fangs are too small to penetrate the skin and are not considered dangerous. (Pat’s note: Dick doesn’t know it, but I go back out and sneak them back in after he goes to sleep.) (Dick’s note. I do now!)
True daddy longlegs, not to be confused with daddy longleg spiders. Images courtesy of Joseph Berger, Colorado State Univ., Bugwood.
These spiders spin untidy webs that are readily abandoned if they become dirty. When webs are abandoned, the spiders immediately spin new webbing, thus accounting for the large amount of webs that can be found in a home with relatively few spiders. The main webbing is relatively weak and typically is not used to trap prey and is primarily used for retreat. Likewise their chelicerae are also too small to hold prey. This spider traps its prey by throwing tough, stiff web material over the victim. After the prey is motionless, it is wrapped and subsequently pumped full of digestive enzymes. These spiders are capable of subduing almost any type of arthropod including larger wolf spiders, black widows and even other daddy longlegs. Even though the average homeowner is unwilling to put up with them, these spiders are quite effective predators and can significantly reduce the presence of other bugs in the home.
In the winter when the general insect population is at its lowest, the spider moves through the house on hunting expeditions. On such occasions it even starts looking for the web of other species of spiders. If found it will vibrate the web (simulating a captured prey) in combination with acting like a captured prey-this behavior includes twitching its abdomen, bouncing in place and shivering and tensing while contracting its legs toward its body. All these behaviors tend to excite the other spider which emerges expecting a capture prey but is consumed by the larger long-legged cellar spider.
Daddy-longleg or cellar spider.
This species originally came from the tropics and in colder climates is found only inside houses. Unlike most other spiders, daddy longlegs breed throughout the year. The fertilized eggs are not spun in a cocoon, but are held in a small net of silk. Because the spider is always on the move, it is common to see a female carrying her sac of 20 to 30 eggs with her.
Brazilian Wandering Spiders Armed Spiders or Banana Spiders-Phoneutria spp. The last name should not to be confused with the relatively harmless species of the genus Nephila. This a genus of aggressive and highly venomous spiders found in tropical South and Central America. These spiders are members of the Ctenidae family of wandering spiders. The genus Phoneutria (Greek for "Murderess") contains eight species. The Brazilian wandering spiders can grow to have a leg span of up to 4 to5 inches. Their body length ranges from 0.7–1.9 inches. The wandering spiders are so-called because they wander the jungle floor at night, rather than residing in a lair or maintaining a web. During the day they hide inside termite mounds, under fallen logs and rocks, and in banana plants and bromeliads. P. nigriventer is known to hide in dark and moist places in or near human dwellings.
Brazilain Wandering Spider. Image Courtesy of Teuchser.
They have a distinctive defensive display in which the body is lifted up into an erect position, the first two pairs of legs are lifted high (revealing the conspicuous black-striped pattern on their underside), while the entire animal sways from side to side.
They are found in forests from Costa Rica throughout South America east of the Andes into northern Argentina, including Colombia,Venezuela, the Guianas, Ecuador, Peru, Bolivia, Brazil and Paraguay. Two species (P. reidyi and P. boliviensis) are found from southern Central America to the Amazon region, while one species (P. fera) is restricted to the Amazon. The remaining species are restricted to Atlantic Forest of Argentina, Paraguay and Brazil, including forest fragments in the Cerrado (savannah). In Brazil, Phoneutria is only absent in the northeastern region north of Salvador, Bahia. Phoneutria has been introduced to Chile and Uruguay.
P. nigriventer is the most venomous species of spider. Its venom contains a potent neurotoxin, known as PhTx3, which acts as a broad-spectrum calcium channel blocker that inhibits glutamate release, calcium uptake and also glutamate uptake in neural synapses. At deadly concentrations, this neurotoxin causes loss of muscle control and breathing problems, resulting in paralysis and eventual asphyxiation. In addition, the venom causes intense pain and inflammation following an attack due to an excitatory effect the venom has on the serotonin 5-HT4 receptors of sensory nerves. This sensory nerve stimulation causes a release of neuropeptides such as substance P which triggers inflammation and pain.
Aside from causing intense pain, the venom of the spider can also cause priapism (prolonged erection of the penis or clitoris-several hours in some cases) in humans. Erections resulting from the bite are uncomfortable, can last for many hours and can lead to impotence. A component of the venom (Tx2-6) is being studied for use in erectile dysfunction treatments.
The amount of P. nigriventer venom necessary to kill a 20 g mouse has been shown to be only 6 μg intravenously and 134 μg subcutaneously as compared to 110 μg and 200 μg respectively for Latrodectus mactans (Black Widow). Laboratory mice subjected to P. nigriventer venom experienced intense penile erections before succumbing to the toxin. This ranks Phoneutria venom among the most deadly found in spiders.
Phoneutria includes some of the relatively few species of spiders known to present a threat to human beings. Danger to humans is not merely a question of toxicity, but requires the capacity to deliver the venom, a sufficient quantity of venom, a disposition that makes a bite likely and proximity to human habitation. The actual incidence of death or serious injury must also be considered.
Spider mouthparts evolved to inject venom into very small prey. They are not well-adapted to attacking large mammals such as humans. Recent studies suggest that Phoneutria inject venom in approximately one-third of their bites, and only a small quantity in one-third of those cases.
Of the eight described species, P. nigriventer and P. fera most frequently receive mention in mass-media publications. P. nigriventer is the species responsible for most cases of venom intoxication in Brazil because it is commonly found in highly populated areas of south-eastern Brazil, such as the states of São Paulo, Minas Gerais, Rio de Janeiro and Espírito Santo. The species P. fera is native to the northern portion of South America in the Amazon of Brazil, Venezuela, Ecuador, Peru and the Guyanas.
The spider's wandering nature is another reason it is considered so dangerous. In densely populated areas, Phoneutria species usually search for cover and dark places to hide during daytime, leading it to hide within houses, clothes, cars, boots, boxes and log piles, thus generating accidents when people disturb its. Its other common name "banana spider" is attributed, because of its tendency to hide in banana bunches on plantations, and is occasionally found as a stowaway within shipments of bananas. These spiders can also appear in banana crates sent to grocery stores and bulk food centers around the world. One such instance happened with a shipment of bananas arriving at Bridegwater, England, when a man was bitten by a P. fera; however, due to quick medical care he survived, taking nearly a week to recover from the bite following treatment.
Despite their reputation as the world's deadliest spiders, there are multiple studies that call in to question their capacity for fatal human envenomation, though some of these are labeled with a level of uncertainty, as Phoneutrias easily can be confused with other species such as the Lycosides or other large labidognatha spiders. One study suggested that only 2.3 % of bites (mainly in children) were serious enough to require antivenom. However, other studies indicated that the toxicity of Phoneutria venom was clearly more virulent than both Latrodectus and Atrax. Many experts believe that various spiders like Phoneutria can either deliver a "dry" bite or purposely conserve their venom, as opposed to a more primitive spider like Atrax that usually delivers a full load. Nevertheless, there are well-attested instances of death. In one case, a single spider killed two children in São Sebastião. The spider was positively identified as a Phoneutria.
Australian Funnel-Web Spider. Familt- Hexathelidae. This family includes an estimated 40 species of Hadronyche and a sole species of the genus Atrax robustus, the notoriously dangerous Sydney funnel-web spider. These spiders are medium-to-large in size, with body lengths ranging from 0.4" to 2 inches. They are darkly colored, ranging from black to brown, with a glossy carapace covering the front part of the body. They have long spinnerets; this is especially true of A. robustus.
Like other Mygalomorphae —an infraorder of spiders that includes the tropical tarantulas —these spiders have fangs which point straight down the body and do not point towards each other. They have ample venom glands that lie entirely within their chelicerae. Their fangs are large and powerful, capable of penetrating fingernails and soft shoes.
Sydney Funnel-Web Spider with
Huge Fangs en:User:Tirin, www.takver.com
Funnel-webs make their burrows in moist, cool, sheltered habitats—under rocks, in and under rotting logs, some in rough-barked trees (occasionally meters above ground). They are commonly found in suburban rockeries and shrubberies, rarely in lawns or other open terrain. A funnel-web's burrow characteristically has irregular silk trip lines radiating from the entrance. Unlike some related trapdoor spiders, funnel-webs do not build lids to their burrows.
The primary range of the Australasian funnel-web spiders is the eastern coast of Australia, with specimens found in New South Wales, South Australia, Victoria, and Queensland. In addition, some specimens have been found in other islands in the south Pacific. The only Australian states without funnel-webs are Western Australia and the Northern Territory.
Funnel-webs are one of the three most dangerous spiders in the world and are regarded by some to be the most dangerous. Examination of bite records has implicated wandering males in most if not all fatal funnel-web bites to humans. Adult males, recognized by the modified terminal segment of the palp, will defend themselves vigorously if they feel threatened and tend to wander during the warmer months of the year looking for receptive females for mating. They are attracted to water and hence are often found in swimming pools where they have fallen while wandering. The spiders can survive such immersion for several hours and can deliver a bite when removed from the water. They also show up in garages and yards in suburban Sydney. Contrary to a commonly held belief, no funnel-web spider is able to jump, although they can run quickly.
While some very venomous spiders may give dry bites, these spiders do so much less frequently. An inefficient mode of delivery (to large animals) and interrupted contact are also possible causes of low volume delivery. It has been claimed that approximately 10% to 25% of bites will produce significant toxicity but the likelihood cannot be predicted and all should be treated as potentially life-threatening.
There have been 26 recorded deaths in Australia in the last 100 years from spider bites. Bites from Sydney funnel-web spiders have caused 13 deaths (seven in children). In all cases where the sex of the biting spider could be determined, it was found to be the male of the species. Most victims were young, ill or infirm. One member of the genus Hadronyche, the northern tree funnel-web has also been claimed to cause fatal envenomation but, to date, this lacks the support of a specific medical report. Assays of venom from several Hadronych species have shown it to be similar to Atrax venom.
There are many different toxins in the venom of Atrax and Hadronyche spiders. Collectively, these spider toxins are given the name atracotoxins (ACTX). These toxins are thought to operate by opening sodium channels. They are pre-synaptic neurotoxins that (via sodium channels) induce spontaneous, repetitive firing of action potentials in autonomic and motor neurons and inhibit neurally mediated transmitted release resulting in a surge of endogenous acetylcholine, nor adrenaline and adrenaline.
Although extremely toxic to primates, the venom appears to be fairly harmless to many other animals. It has been suggested that these animals may be resistant to the venom's effects due to the presence of IgG, and possibly cross-linked IgG and IgM inactivating factors in their blood plasma that bind to the toxins responsible and neutralize them, or it may involve a non-specific reaction due to the highly basic nature of the toxins.
The female venom was thought to be only about a sixth as potent to humans as that of the male but recent research has proven that false. The bite of a female or juvenile may be serious; however, considerable variability occurs in venom toxicity between species, together with assumable degrees of inefficiency in the method of venom delivery.
Envenoming symptoms observed following bites by these spiders are very similar. The bite is initially very painful, due to the acidity of the venom and the size of the fangs penetrating the skin. Systemic envenoming may follow the local effects. Early symptoms of systemic envenoming include tingling around the mouth and tongue, facial muscle twitching, nausea, vomiting, profuse sweating, salivation, and shortness of breath. Patients may rapidly develop agitation, confusion and coma associated with hypertension, metabolic acidosis, dilation of the pupils, generalized muscle twitching and pulmonary aedema. Death results from progressive hypotension or possibly raised intracranial pressure consequent of cerebral swelling.
The onset of severe envenoming can be rapid. In one prospective study, the median time to onset of envenoming was 28 minutes, with only two cases having onset after 2 hours (both had pressure immobilization bandages applied). Death may occur within a period ranging from 15 minutes (this occurred when a small child was bitten) to three days.
First aid for funnel-web bites consists of applying a pressure immobilization bandage. Pressure immobilization is the wrapping of the bitten limb with a crepe bandage and splint. It was originally developed for snake bites but has been shown to be effective at slowing venom movement in funnel-web bites and may also slowly inactivate the venom.
Further supportive care may be necessary, but the mainstay of treatment is antivenom. Antivenom is raised against male Atrax robustus venom but appears to be effective for all species of funnel web spiders. Funnel-web antivenom has also been shown to reverse the in vitro effects of Eastern Mouse spider (Missulena bradleyi) venom.
Prior to the introduction of antivenom, envenoming resulted in significant morbidity and mortality. Fortunately, the antivenom is fast-acting and highly and globally effective. Antivenom therapy has shortened the course of envenoming: prior to antivenom availability, the average length of hospital treatment for severe bites was about 14 days. Today, antivenom-treated patients are commonly discharged from hospital within 1 to 3 days. There have been no known deaths since it became available.
Six-Eyed Sand Spider-Sicarius hahni. This is a medium-sized spider with body measuring 1/3 to 2/3 inch in length and legs spanning up to 2 inches. It is a South African living fossil that pre-dates the Gondwanaland drift some 100 million years ago and also occurs in South America. It is found in deserts and other sandy places in southern Africa. It is a member of the Sicariidae family; close relatives may be found in both Africa and in South America, and its near cousins, the recluses (Loxosceles), are found worldwide. Due to its flattened stance and laterally attached legs, it is also sometimes known as the six-eyed crab spider. Bites by Sicarius are uncommon; there are no proven cases and only two suspected cases where the culprit was never identified. Sicarius bites have been experimentally shown as lethal to rabbits within 5 to 12 hours. The genus name Sicarius is Latin for 'murderer, from sica, a curved dagger.
This spider buries itself in the sand and strikes from ambush at prey that wanders too closely. Sand particles adhere to cuticles on its abdomen, thus acting .s a natural camouflage if uncovered. If disturbed, it will run a short distance and bury itself again.
Toxicology studies have demonstrated that the venom is particularly potent, with a powerful hemolytic/necrotoxic effect, causing blood vessel leakage, thinning of the blood and tissue destruction. Sicarius bite treatment should be directed, as with all cytotoxic bites, at prevention of secondary infection and combating disseminated intravascular coagulation (DIC) if it develops.
Six-Eyed Crab Spider. Courtesy EcoPort
Because these critters are some of the larger and most commonly encountered arthropods on the planet, it follows that there are considerable myths and falsehoods associated with them. One very common belief in many parts of Central and South America is that when a spider urinates on a horse, its hoof will fall off. In such regions, children are given the task of collecting and killing all spiders around horse corrals. In actuality, horse's hooves are susceptible to splitting and even "falling off," which in extreme cases leaves the animal lame for life. This phenomenon is referred to as "founder," but is by no means due to spider pee, as spiders do not pee and in most cases their feces is quite dry. Keep in mind that one of the main physiological battles of these creatures is the loss of water and any excess water in the feces would be adding to this problem. Founder can result from any extreme tissue damage occurring on any part of the body. If this occurs, chemical messages are produced that cause the blood vessels in the hoof (and other parts of the body) to constrict, resulting in splitting of the hoof. It is possible that if a horse were to be bitten by a very toxic spider (which could cause tissue damage), founder might occur.
In some American Indian cultures, Spider Woman is a cautionary figure used by mothers to warn unruly children. Spider Woman is a protector to the Navajo. She instills a type of spiritual protection and, as a creator, a love of beauty. The comparison of an intricate and elaborate orb web to a beautiful tapestry is not hard to make. Spider Woman, being a spinner, is represented by a tiny hole found in all traditional Navaho blankets that indicates the spot where she can escape.
Gaia culture portrays the spider as a sort of earth goddess, a spinner of life and death: a positive figure. The Greco-Romans put a far darker slant to this deft weaver: known as Arachne. Athena, the Goddess of Crafts, turns her into a spider. The story goes that after a contest of skillful weaving, Athena is enraged by the subject of Arachne's tapestry--a portrayal of the gods, especially Zeus (highest god of all and Athena's father), in an unflattering light. After condemning her to hang until dead, Athena spared her life but turned her into a spider--dangling from a web instead of a noose. Arachne is the reason that spiders are known as Arachnids.
Tarantulas are hairy behemoths of the American spider world. In southern Italy, the name "tarantula" came into usage in the town of Taranto. A local large wolf spider was considered to be extremely venomous. The legend was that if this spider bit someone, they must begin dancing to a lively song known as the tarantella or they would fall into a coma. The spider became known as "tarantula." This particular spider is not really very venomous and the others we know as tarantulas usually aren't either. But their size alone is enough to give some people nightmares.
In Ancient Egypt, the spider was associated with the goddess Neith in her aspect as spinner and weaver of destiny, this link continuing later through the Babylonian Ishtar and Greek Athena. It is the story of the weaving competition between the Greek goddess Athena and the sometimes princess Arachne. This fable was added much later to the Greek mythos when Ovid wrote the poem Metamorphoses between AD 2-8. Arachne was the daughter of a famous Tyrian purple dyer in Hypaipa of Lydia. Due to her father's skill with cloth dying, Arachne was adept in the art of weaving. Eventually, she began to consider herself a greater weaver than the goddess Athena herself and challenged the goddess to a weaving contest to prove her skill. Athena wove the scene of her victory over Poseidon that had inspired her patronage of Athens, while Arachne wove a tapestry featuring twenty-one episodes of infidelity amongst the Gods of Olympus, which angered Athena. The goddess conceded that Arachne's weaving was flawless but she was infuriated by the mortal's pride. In a final moment of anger, Athena destroyed Arachne's tapestry and loom with her shuttle and cursed Arachne to live with extreme guilt. Out of sadness, Arachne hanged herself soon after. Taking pity on her, Athena brought her back to life as a spider (using juice of aconite) after the princess killed herself. Athena made sure that the spider retained Arachne's weaving abilities. The Greek Arachne means "spider" (αράχνη).
An Islamic tradition holds that during the Hijra, the Prophet Muhammad and his companion Abu Bakr took refuge in a cave whilst being pursued by the Quraysh. The tale goes on to say that God commanded a spider to weave a web across the opening of the cave and a dove to construct a nest in front of it, thus deterring the Quraish from entering (the Prophet's entry to the cave would have broken a web). Since then, it is held in many Muslim traditions that spiders are, if not holy, then at least to be respected.
The 10th Century Saint Conrad of Constance is sometimes represented as a bishop holding a chalice with a spider in it or over it. This refers to a story that once when he was celebrating mass a spider fell into the chalice. Spiders were believed at that time to be deadly poisonous, but Conrad nevertheless drank the wine, with the spider in it, as a token of faith.
In more recent history, the famous legend of the King Robert the Bruce of Scotland depicts a spider as a symbol for hope. Historians are unsure of the legend's truth but in the legend Bruce, when fighting the English, took refuge in a cave after a series of military failures. While hiding in the cave he saw a spider, which continued to fail to climb up its silken thread to its web. After repeatedly failing to climb upwards, the spider eventually succeeded due to perseverance. Taking this as a symbol for hope and perseverance, much like the saying "try, try and try again", Bruce came out of hiding. Bruce eventually won Scotland's independence.
The spider has been compared with vampires as they have similar characteristics. Both lure and ensnare prey before sucking the life out of their victim. Like the arachnids, vampires are believed to be able to scale walls and cliff faces, and possess fangs, similar to those of spiders.
The spider is also depicted in various urban legends. The daddy long legs (Pholcidae) were known as to have very potent venom but have very short fangs to deliver the poison. The myth might have arisen due to its similarity in appearance with the Brown recluse spider. However, an episode in Discovery Channel's Myth Busters indicated that a host was able to survive a bite from the spider. Another urban myth depicts a young woman who found out that her beehive hair was infested with Black widow spiders. An email hoax describes the attacks by the South American Blush Spider in public toilets. The alleged spider's scientific name Arachnius gluteus literally means "butt spider". It should be noted that the hoax spider shares some characteristics with the two-striped telamonia (Telamonia dimidiata).
The spider has been featured in literature for many centuries. In the Vedic philosophy of India, the spider is depicted as hiding the ultimate reality with the veils of illusion. In the epic poem Ovid's Metamorphoses written about 2millennia ago. In Chinese fantasy, Wu Cheng'en'sJourney to the West, spiders came as female monsters. They tried to eat Xuánzàng, but it failed. Spiders were also depicted in Dante Alighieri'sPurgatorio as the half-spider Arachne, and more recently in books such as the fantasy novel Harry Potter and the Chamber of Secrets by J. K. Rowling. This book was later followed by a motion picture of the same name, using the giant spider Aragog from the novel as a supporting character and pet of Hagrid, a grounds keeper in the book. Again in titles such as The Lord of the Rings, written by J. R. R. Tolkien, the spider takes its form as the menacing giant spider Shelob, and was featured in the film adaption of the last book of the Lord of the Rings series. Tolkien had previously used spiders in his precursor to the Lord of the Rings series with the book The Hobbit. In The Hobbit, giant spiders roamed a great forested area known as Mirkwood and attacked the main characters of the book, capturing some of them. Spiders are a recurring theme in both Tolkien's works and in other authors. The 1952 children's novel Charlotte's Web written by E. B. White, later made into a feature film in 1973 and 2006, is notable in its portrayal of the spider in a positive manner as a heroine rather than an object of fear or horror. Atlach-Nacha is the creation of Clark Ashton Smith and first appeared in his short story "The Seven Geases" (1934). Atlach-Nacha resembles a huge spider with an almost-human face. In the story, Atlach-Nacha is the reluctant recipient of a human sacrifice given to it by the toad-god Tsathoggua.
In graphic novels, spiders are often adapted by superheroes or villains as their symbols or alter ego due to the arachnid's strengths and weaknesses. One of the most notable characters in comic book history which has taken their identity and name from the spider is the Marvel comic book hero Spider-Man. After being accidentally bitten by a radioactive spider, Peter Parker, later known as Spider-Man, was able to scale tall buildings and shoot web fluid from a box attached to his wrist. Along with these abilities came super senses and instant reflexes. The franchise, originally created by the writer Stan Lee and artist Steve Ditko, has become so popular that it has had three successful movies made based on the Spider-Man comic books. Along with Spider-Man, the comic book has also introduced several new characters using the spider as their patron: these include Spider-Woman, Spider-Girl, theScarlet Spider, Venom, Araña, and the Tarantula. Many other comic book characters have taken the guise of a spider, including Black Spider from the Batman universe, and in manga and anime; In the Pokémon franchise, Spinarak and Ariados are similar to spiders in shape; in the Static Shockseries, Anansi the Spider takes his name and techniques from the African trickster god.
Questions for pest control continuing education requirements.
8. The black widow spider’s web is somewhat unique and can readily be detected due to the fact that it is asymmetrical in shape and strong.
9. Black widows are typically found in situations that are brightly lit, humid and have a supply of food.
10 The chances of an adult human dying from a black widow spider bite are high if not treated medically.
11. The bite of a brown recluse spider typically results in a large sore that continues to enlarge and takes a long time to heal
12. Most spider experts feel that the brown recluse spider is no longer present in California.
13. It is quite possible that the cases of brown recluse spider bites that have been recorded by the medical community in California were actually due to other spiders such as the hobo or yellow sac spiders.
14. One of the ways a tarantula protect itself from a potential predator is to kick finely branched hairs off its abdomen into the air which in turn may get into the eyes, lungs or skin of the attacker causing itching and distress.